i Work perfecly,
my step is:
Download the system update system-update-usb , that zip file (SystemUpdate_XXXXX_USB.zip) will same name of your Dashboard: 2.0.XXXXX.0, where X = your current dashboard/kernel version).
Format Flashdisk to FAT32
Extract Zip file
Copy $SystemUpdate to root Flashdisk
and copy again to root but rename the second folder to $$ystemUpdate
so you will have two folder on FAT32 Flashdisk $SystemUpdate and $$ystemUpdate
Put Flashdisk on Xbox
Turn in On the Xbox
Run Kinect Games
than will show the prompt, remember only "Yes" for Prompt with "Update Required", if Prompt is "System Update" choose "No"
I Hope this can Help...